Faulty communication OTGW between thermostaat en boiler

[florisj]

Hi, I have just bought a new OTGW and connected it according the description. Just cut the current wiring between my opentherm thermostaat (R8810) and my central heater (Intergas HR). Connected the 2 wires from the heater to the left connections (Boiler) and the 2 wires from the thermostat to the right connections. After that the heater seems to get a signal (or shortcut, gives the same result) to start heating at 100%. At the thermostat end, the R8810 seems to get the right voltage, but start giving a red signal after some time. In the bos is shows 4 leds burning (Same as they do when nothing is connected, so status doesn't change with connecting the wires).
I would appreciate some idea's suggestions to get this to work. Or maybe it is just a DOA. (Dead on Arrival).

[hvxl]

I have created the trouble shooting instructions for precisely this kind of situation.